Cockpit transcript released in search for Malaysia Airlines Flight 370

A Royal New Zealand Air Force P-3 Orion's co-pilot and Squadron Leader Brett McKenzie controls the pane while searching for the missing Malaysia Airlines Flight MH370 in the southern Indian Ocean, Monday, March 31, 2014.

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ROB GRIFFITH and ROD McGUIRK Associated Press

PERTH, Australia | Investigators are conducting a forensic examination of the final recorded conversation between ground control and the cockpit of Malaysia Airlines Flight 370 before it went missing three weeks ago, the Malaysian government said Tuesday. Meanwhile Australia, which is coordinating the search for the Boeing 777, cautioned that it "could drag on for a long time" and would be an arduous one.

The forensic examination could shed light on who was in control of the cockpit and will also seek to determine if there was any stress or tension in the voice of whoever was communicating with ground control — crucial factors in an air disaster investigation.

Responding to repeated media requests, the Malaysian government also released a transcript of the conversation, which showed normal exchanges from the cockpit as it requested clearance for takeoff, reported it had reached cruising altitude and left Malaysian air space.

"Good Night Malaysian three-seven-zero," were the final words received by ground controllers at Kuala Lumpur's international airport at 1:19 a.m. on March 8. On Monday, the government changed its account of the final voice transmission which it had earlier transcribed as "All right, good night."

The three-week hunt for Flight 370 has turned up no sign of the jetliner, which vanished March 8 with 239 people on board bound for Beijing from Kuala Lumpur.

The search zone area has shifted as experts analyzed the plane's limited radar and satellite data, moving from the seas off Vietnam to the waters west of Malaysia and Indonesia, and then to several areas west of Australia. The current search zone is a remote 254,000 square kilometer (98,000 square mile) that is a roughly 2 ½-hour flight from Perth.

On Tuesday, Australia said it had deployed an airborne traffic controller over the Indian Ocean to prevent a mid-air collision among the many aircraft searching for the jetliner.

An Australian air force E-7A Wedgetail equipped with advanced radar "is on its first operational" task in the search area in the middle of the Indian Ocean, the Australian Maritime Safety Authority said in a tweet. Earlier, Angus Houston, who heads the joint agency coordinating the multinational search effort, said the modified Boeing 737 will monitor the increasingly crowded skies over the remote search zone.

On Tuesday, 11 planes and nine ships were focusing on less than half of the search zone, some 120,000 square kilometers (46,000 square miles) of ocean west of Perth, with poor weather and low visibility forecast, according to the new Joint Agency Coordination Center. A map from the center showed that the search area was about 2,000 kilometers (1,200 miles) west of Perth.

Some of the aircraft have been dropping as low as 200 feet (60 meters) above the water — and occasionally dipping even lower for brief periods — raising concerns of collisions with ships that are crisscrossing the zone.

Under normal circumstances, ground-based air traffic controllers use radar and other equipment to keep track of all aircraft in their area of reach, and act as traffic policemen to keep planes at different altitudes and distances from each other. This enforced separation — vertical and horizontal — prevents mid-air collision. But the planes searching for Flight 370 are operating over a remote patch of ocean that is hundreds of kilometers (miles) from any air traffic controller.

The arrival of the E-7A "will assist us with de-conflicting the airspace in the search area," Houston told reporters in Perth. The plane can maintain surveillance over a surface area of 400,000 square kilometers (156,000 square miles) at any given time, according to the air force's website.

Houston, a former Australian defense chief, called the search effort the most challenging one he has ever seen. The starting point for any search is the last known position of the vehicle or aircraft, he said.

"In this particular case, the last known position was a long, long way from where the aircraft appears to have gone," he said. "It's very complex, it's very demanding."

"What we really need now is to find debris, wreckage from the aircraft," he said. "This could drag on for a long time."

Malaysia has been criticized for its handling of the search, particularly its communications to the media and families of the passengers. In its latest misstep, the government on Monday changed its account of the final voice transmission from the cockpit.

In Tuesday's statement, the government said that police and forensic examinations were trying to confirm if the voice belonged to the co-pilot as was earlier believed.

"There is no indication of anything abnormal in the transcript," Malaysia's acting Transport Minister Hishamuddin Hussein said in the statement.

Australian Prime Minister Tony Abbott has said that although the search for the aircraft has been slow, difficult and frustrating — it will continue indefinitely. In fact, he said the intensity and magnitude of operations "is increasing, not decreasing."

"If this mystery is solvable, we will solve it," Abbott said.

Items recovered so far were discovered to be flotsam unrelated to the Malaysian plane. Several orange-colored objects spotted by plane Sunday turned out to be fishing equipment.